Not necessarily, the component itself can work without a key. Adding a key is just one approach to resetting component state from a parent. If a component can’t work properly without a key it should be wrapped further to make it usable rather than documenting it for all consumers.
That last bit seems like a recommendation that should be in the docs. It’s sensible from a “don’t leave boobytraps” perspective but it won’t be intuitive to many people. It’s one more little rule to learn, another comment on a sizable chunk of PRs. While it may be idiomatic and sensible JSX, it seems like an outlier for React, and I wonder if there’s an opportunity to improve the developer experience of this very common use case.
